1. Field of the Invention
The present invention generally relates to detection of wildfires, and in particular to use of analysis of visible range camera sensors to determine the presence of wildfires.
2. Background Description
The prior art of relevance to detection of wildfires includes the following references:
United States Patent Publication No. 2005/0001729 for “System and method for fire detection” to William R. Garmer et al. (“Garmer '729 application”) dated Jan. 6, 2005, describes a system based on detecting electromagnetic radiation with a flicker frequency less than 10 Hz due to flames. On the other hand, smoke arises first in wildfires and become visible over the trees or bush from long distances. Smoke does not flicker as flames, therefore flicker frequency analysis will not help to distinguish smoke from other sources of electromagnetic energy. Obviously smoke is not an energy source. Therefore, the Garmer '729 application cannot detect smoke.
U.S. Pat. No. 7,256,401 for “System and method for fire detection” to Garmer, et al. (“Garmer '401”) issued Aug. 14, 2007, also uses a sensor detecting electromagnetic radiation. Unfortunately, flames are not visible in early stages of fire because the fire starts from the ground and as a result infrared radiation is not detectable at the very early stage of the fire.
United States Patent Publication No. 2008/0309502 by Henri Boccia et al. (“Boccia '502”) dated Dec. 18, 2008, describes a system in which sensors are installed in trees. Sensors detect fires in the vicinity and inform neighboring sensors which in turn produces an alarm. To cover larger forests with ordinary temperature sensors would be very costly.
U.S. Pat. No. 7,164,468 to Correia Da Silva Vilar, et al. issued Jan. 16, 2007 and United States Patent Publication No. 2008/0198025 by Pedro Manuel Cordoso Vieira et al. dated Aug. 21, 2008 use the laser radar LIDAR and optical spectroscopy for wildfire detection. These are expensive technologies.
U.S. Pat. No. 7,541,938 to Engelhaupt issued Jun. 2, 2009 describes a flame detection method. Similarly, U.S. Pat. No. 7,123,154 to Smith issued Oct. 17, 2006 uses UV sensors for flame detection. Neither of these references involve smoke detection.
U.S. Pat. No. 7,460,056 to Rivas et al. issued on Dec. 2, 2008 uses a radar based sensor for wild fire detection. A radar is more expensive than a regular PTZ camera.
What is needed is a system that will detect a wild fire at an early stage of the fire's development, and do so using relatively inexpensive sensor equipment.